Evaluating the Effect of High RAP Content on Asphalt Mixtures and Binders Fatigue Behavior
Evaluating the Effect of High RAP Content on Asphalt Mixtures and Binders Fatigue Behavior

Author: Umme Amina Mannan

Publisher:

Published: 2018

Total Pages: 13

ISBN-13:

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One of the main concerns with the application of reclaimed asphalt pavement (RAP) in the asphalt concrete pavement is fatigue cracking due to the stiffness increase with the addition of aged and stiff RAP binder. The purpose of this study is to evaluate fatigue performance of asphalt binder and mixtures with different RAP percentages (0, 15, 25, 35 and 40 %). Among these, 35 and 40 % RAP mixes are considered as high RAP content. This study describes the results of laboratory fatigue response of asphalt mixtures and extracted binders containing RAP to define the effect of RAP on the fatigue performance. To achieve this objective, mixes and binders were tested using the beam fatigue test and the time-sweep test, respectively. Test results were analyzed using two different fatigue approaches, reduction in stiffness and dissipated energy criteria. Results showed that a higher initial stiffness and initial dissipated energy initiate the fatigue failure faster. Since both binders and mixes show an increase in the stiffness and energy consumed per loading cycle with the addition of RAP, resulting mixes containing higher RAP have a very short fatigue life. Also, the fatigue endurance limit decreases drastically with the addition of RAP in the mix. The results comparing two different RAP sources showed that the RAP source has more prominent effect on the mix fatigue performance than the binder fatigue performance. Finally, the traditional fatigue life prediction model is modified to incorporate the effect of RAP in the fatigue equation. The modified regression model predicted reasonable fatigue life of the mixture with a coefficient of determination (R2) close to 1. The measured and predicted fatigue life results were found close to each other for both mix and binder containing RAP.

Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content
Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content

Author: Randy Clark West

Publisher: Transportation Research Board

Published: 2013

Total Pages: 162

ISBN-13: 0309259134

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TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.

Fatigue and Stiffness Evaluations of Reclaimed Asphalt Pavement in Hot Mix Asphalt Mixtures
Fatigue and Stiffness Evaluations of Reclaimed Asphalt Pavement in Hot Mix Asphalt Mixtures

Author: Feipeng Xiao

Publisher:

Published: 2011

Total Pages: 9

ISBN-13:

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The recycling of existing asphalt pavement materials produces new pavements with considerable savings in material, money, and energy. Understanding the ability of an asphalt pavement containing reclaimed asphalt pavement (RAP) to resist fracture from repeated loads is essential for the design of hot mix asphalt (HMA) mixtures. However, reaching a better understanding of fatigue behaviors of these pavements continues to challenge researchers all over the world, particularly, as recycled materials with more complex properties are being used in HMA pavements. This study explores the utilization of the conventional fatigue analysis approach in investigating the fatigue life of asphalt mixtures containing RAP. The fatigue beams were made with two asphalt binders, two aggregate sources, four RAP contents (0 %, 15 %, 25 %, and 30 %), and tested at 5 and 20°C. A total of eight mixtures was evaluated and 64 fatigue beams were tested in this study. The test results indicated that the addition of RAP, as expected, increased the viscosity, G*sin?, and creep stiffness values while reducing the m-values. However, no obvious trends were found for stiffness and fatigue life of mixtures as the RAP content increased. Statistical analysis results indicated that for binders and mixtures containing 30 % RAP, the utilization of softer binder significantly decreased the viscosity, G*sin?, and creep stiffness values; however, there were no significant differences in the stiffness and fatigue life values of these mixtures.

Laboratory Evaluation of Asphalt Concrete Mixtures Containing High Contents of Reclaimed Asphalt Pavement (RAP) and Binder
Laboratory Evaluation of Asphalt Concrete Mixtures Containing High Contents of Reclaimed Asphalt Pavement (RAP) and Binder

Author:

Publisher:

Published: 2014

Total Pages: 38

ISBN-13:

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This study investigated the effect of added asphalt binder content on the performance and volumetric properties of asphalt concrete mixtures containing reclaimed asphalt pavement (RAP) in the amounts of 0%, 20%, and 40%. A laboratory-produced mixture containing 100% RAP was also evaluated. Performance of the mixtures was evaluated based on three criteria: stiffness (dynamic modulus), fatigue resistance, and rutting resistance (flow number and asphalt pavement analyzer). Results showed that a 0.5% increase in binder content improved both the fatigue and rutting resistance of the 0% and 20% RAP mixtures with only slight (insignificant) decreases in dynamic modulus. However, the addition of various amounts of binder to the 40% RAP mixture led to a significant decrease in rutting resistance with little or no improvement to fatigue resistance. Volumetric analysis was performed on all of the mixtures, and detailed results are presented. Based on the results of the study, the authors recommend that the Virginia Department of Transportation supplement current asphalt mixture design procedures that are based on mixture volumetric properties with laboratory-mixture performance testing.

Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios
Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios

Author: Amy Epps Martin

Publisher:

Published: 2020

Total Pages: 284

ISBN-13: 9780309481045

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"More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--

Development of an Asphalt Damage Characterization System Using Laser Scanning Detection Technology
Development of an Asphalt Damage Characterization System Using Laser Scanning Detection Technology

Author: Hossein Ajideh

Publisher:

Published: 2011

Total Pages: 282

ISBN-13: 9781124677347

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Fatigue damage is a major distress in asphalt pavement and has been evaluated using various experimental and analytical approaches over the last two decades. However, a better understanding of fatigue behavior is needed for improved design and repair methods to minimize failures. The first objective of the present research was to develop a new non-contact damage characterization technique to monitor fatigue behavior of asphalt mixes using laser scanning detection system. The second objective of the study was to evaluate the capability of the new technique for measuring the effect of engineered binders modified by a special reaction technique on critical fatigue damage resistance properties. The third and final objective was to investigate mixtures produced with high percentage of Reclaimed Asphalt Pavement (RAP) for damage resistance and compared to the mixes produced with un-modified and modified binders. The laser scanning technique is a non-contact measuring system that detects changes in surface properties using a parameter called "defect frequency" by scanning a laser beam along the specimen surface. The results of the present laser scanning method were compared to the data obtained from other traditional measuring systems using conventional deflection measuring devices. Analysis of data included the defect frequency and the change in mechanical properties in terms of reduction in initial stiffness, as well as dissipated energy approaches (Ratio of dissipated energy and Energy Ratio). Fatigue resistance and material response of several mixes were investigated in the present work under various cyclic uniaxial tensile loading conditions by monitoring the intensity of scattered light from the specimen surface. The laser scanning results indicate that this technique is capable of effectively capturing crack initiation and propagation processes. Defect frequency data exhibit excellent agreement with changes in mechanical capacity and dissipated energy properties as damage develops. The number of cycles to failure indicated by laser scanning correlated well with that obtained from traditional and dissipated energy methods. An analysis of the results also reveals superior performance of the modified binders in terms of fatigue resistance, when compared to the base binder. The mixtures produced with the engineered binders and with high RAP content offer better resistance to damage for a wide range of simulated pavement strain amplitudes.